首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2161篇
  免费   154篇
  国内免费   176篇
安全科学   469篇
废物处理   41篇
环保管理   407篇
综合类   809篇
基础理论   228篇
环境理论   3篇
污染及防治   228篇
评价与监测   88篇
社会与环境   99篇
灾害及防治   119篇
  2024年   6篇
  2023年   23篇
  2022年   20篇
  2021年   35篇
  2020年   51篇
  2019年   53篇
  2018年   54篇
  2017年   81篇
  2016年   92篇
  2015年   83篇
  2014年   105篇
  2013年   159篇
  2012年   127篇
  2011年   161篇
  2010年   129篇
  2009年   131篇
  2008年   113篇
  2007年   133篇
  2006年   140篇
  2005年   114篇
  2004年   89篇
  2003年   103篇
  2002年   70篇
  2001年   63篇
  2000年   72篇
  1999年   56篇
  1998年   35篇
  1997年   24篇
  1996年   26篇
  1995年   16篇
  1994年   15篇
  1993年   13篇
  1992年   9篇
  1991年   7篇
  1990年   8篇
  1989年   7篇
  1988年   9篇
  1987年   3篇
  1986年   4篇
  1985年   3篇
  1984年   7篇
  1983年   3篇
  1982年   6篇
  1980年   6篇
  1979年   4篇
  1978年   5篇
  1976年   3篇
  1974年   2篇
  1972年   3篇
  1971年   4篇
排序方式: 共有2491条查询结果,搜索用时 15 毫秒
941.
分析了利用新的测绘技术进行土地整理规划的优势,简要介绍了3S技术,提出采用3S技术获取土地整理基础信息的基本技术路线,详细说明了RS,GPS,GIS技术在土地整理调查、成图、规划设计过程中的应用,指出3S技术一体化为提高土地整理规划决策的实效性,大幅度地降低财力的投入提供了新的方法。  相似文献   
942.
太阳能技术在住宅建筑中的应用   总被引:3,自引:1,他引:2  
太阳能技术的应用对我国住宅产业的发展具有重要意义。文章分析了目前国际和国内住宅建设领域中太阳能技术的应用形式与局限,指出了我国实现太阳能住宅建筑一体化进程中应着重解决的主要问题。  相似文献   
943.
山西省重点污染源自动监控系统是集环境监测、监视和控制于一体的污染源自动监控系统,解决了传统污染源监控系统"只监不控"、"只监结果不监过程"的问题。介绍了该系统的组成、功能及技术特点,并于2010年3月通过该系统对超标排放企业远程监控的实施情况进行了分析。结果表明,该系统能够有效对监控企业进行实时监测,并对污染超标企业进行远程控制和警示,从而有效提高了环境监管水平和执法效率,加强了防止和应对突发性重大环境污染事故的能力。  相似文献   
944.
为了将民用电磁炉灶应用于舰船环境,尤其是水下近距离非接触爆炸的诱发冲击环境,针对其环境适应性进行了重新设计.论述了舰用电磁炉灶抗冲击的设计要求,提出了舰用电磁炉灶抗冲击设计方法,并通过舰用电磁炉灶抗冲击试验验证了设计的合理性.  相似文献   
945.
Linking Theory and Practice for Restoration of Step-Pool Streams   总被引:1,自引:0,他引:1  
Step-pools sequences are increasingly used to restore stream channels. This increase corresponds to significant advances in theory for step-pools in recent years. The need for step-pools in stream restoration arises as urban development encroaches into steep terrain in response to population pressures, as stream channels in lower-gradient areas require stabilization due to hydrological alterations associated with land-use changes, and as step-pools are recognized for their potential to enhance stream habitats. Despite an increasingly voluminous literature and great demand for restoration using step-pool sequences, however, the link between theory and practice is limited. In this article, we present four unique cases of stream restoration using step-pools, including the evolution of the approaches, the project designs, and adjustments in the system following restoration. Baxter Creek in El Cerrito, California demonstrates an early application of artificial step-pools in which natural adjustments occurred toward geomorphic stability and ecological improvement. Restoration of East Alamo Creek in a large residential development near San Ramon, California illustrates an example of step-pools increasingly used in locations where such a channel form would not naturally occur. Construction of a step-pool channel in Karnowsky Creek within the Siuslaw National Forest, Oregon overcame constraints posed by access and the type and availability of materials; the placement of logs allowed natural scouring below steps. Dry Canyon Creek on the property of the Mountains Restoration Trust in Calabasas, California afforded a somewhat experimental approach to designing step-pools, allowing observation and learning in the future. These cases demonstrate how theories and relationships developed for step-pool sequences over the past two decades have been applied in real-world settings. The lessons from these examples enable us to develop considerations useful for deriving an appropriate course of design, approval, and construction of artificial step-pool systems. They also raise additional fundamental questions concerning appropriate strategies for restoration of step-pool streams. Outstanding challenges are highlighted as opportunities for continuing theoretical work.  相似文献   
946.
Subwet模型在人工湿地设计中的应用   总被引:1,自引:0,他引:1  
李慧峰  黄津辉  林超 《环境科学》2013,34(7):2628-2636
针对人工湿地的设计问题,介绍了水平潜流人工湿地的运行机制和设计准则,提出了利用人工湿地数字模型Subwet辅助设计的方法.利用Subwet模型对水平潜流人工湿地的设计进行了模拟,根据模拟结果对影响人工湿地处理效率的因素进行了分析和探讨,并据此对人工湿地的设计优化提出了指导意见.该Subwet模型的应用实例表明人工湿地模型可以应用于设计中,并可为人工湿地设计提供一定的理论指导.  相似文献   
947.
Introduction: Design of next-generation ambulance patient compartment requires up-to date anthropometric data of emergency medical service providers (EMSP). Currently, no such data exist in the U.S. A large-scale anthropometric study of EMSP in the U.S. were conducted. This report provided the summary statistics (means, standard deviation, and percentiles) of the study’s results and examined the anthropometric differences between the EMSP dataset and the U.S. general population, and between the EMSP dataset and U.S. military personnel dataset, respectively. Method: An anthropometric study of 471 male and 161 female EMSP from across the continental US was conducted, using a sampling strategy that took into account age, sex, and race strata. Results: On average, male EMSP were found to be 18 mm taller and 7 kg heavier than US male general population, and 19 mm taller and 11 kg heavier than US male military personnel. Female EMSP were found to be 25 mm taller than US female general population, and 10 kg heavier than US female military personnel. Conclusions: These results showed that it would be inappropriate to apply general population or military data to the design of next-generation ambulance patient compartment. This new dataset provided the most recent and accurate EMSP anthropometric measurements available in the US. Practical Application: Data from this study provided an invaluable resource for the design of next-generation ambulances in the US.  相似文献   
948.
The numerous formulated products which are introduced to the market consist of chemical ingredients that may cause various safety and health hazards to the consumers. Therefore, it is extremely important to practice a systematic methodology to formulate products with acceptable safety and health performances. This work presents an index-based methodology to assess the safety and health hazards of the ingredients during the early formulation stage of product design. Hence, new inherent safety and health sub-indexes are introduced to improve the current safety and health hazards that are needed in formulated product design. The inherent safety and health sub-indexes are assigned with scores based on the degree of potential hazards. A higher score indicates a higher safety risk or severe health effect, and vice versa. The proposed methodology will greatly assist the users to identify the adverse safety and health effects caused by the ingredients. Hence, it is pivotal to eliminate or reduce the safety and health impacts from product usage. A case study on common ingredients used in the formulation of paint is presented on this study to describe the proposed method.  相似文献   
949.
为了解决高温作业环境下安全帽内部微环境积热严重问题,运用ANSYS软件模拟分析了安全帽内部微环境积热的空间和时间分布情况。基于模拟结果,设计了一款分离式可降温安全帽,其由帽体、喷嘴、风管、风机和开关组成。在高温高湿环境下,模拟人员分别佩戴在帽衬带上装有温度传感器的普通安全帽和分离式可降温安全帽进行剧烈运动模拟高温作业人员高强度劳动,记录其温度变化。结果表明:分离式可降温安全帽有良好的降温效果,同时具有不破坏安全帽的结构和强度,几乎不增加安全帽重量,无噪声、无电磁辐射,拆装简便等优点。  相似文献   
950.
The exploitation of a low-quality gas field with high CO2 concentration is more viable through liquid CO2 produced from cryogenic distillation technology. Despite the bright potential of the technology, there are deficiencies in handling high concentration of CO2 at low temperature and high pressure during the blowdown condition. This study focuses on the CO2 blowdown at a cryogenic pilot plant designed to manage high concentrations of CO2 in the feed gas, high pressures, and low temperatures. A comprehensive design review and risk assessment using Inherent Safer Design (ISD) indexes were carried out in this study. The ISD was performed to identify the current risk level, and the critical parameters that may cause solid CO2 formation in the piping or equipment as well as to identify mitigation measures to avoid the temperature to drop below the CO2 freezing point during blowdown. The present findings confirmed that the initial pressure and temperature, as well as CO2 concentration are key parameters towards significant impact on blowdown conditions. Therefore, the reduction of the feed gas pressure from 80 bar to 70 bars has minimized the Joule Thomson (JT) effect during blowdown and avoided the CO2 solid formation in the system. Moreover, the relocation of the blowdown valve at the downstream heater resulted in a higher final temperature above the CO2 freezing point. The ISD indexes confirmed that the cryogenic facilities are inherently safer during blowdown with the mitigation measures adopted.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号